Cover demo area with garbage bags or perform in a clear, plastic box. This demo can be messy!
Pour ~50-100mL 3% H2O2 into one graduated cylinder and ~50-100mL 30% H2O2 into the other.
Add a squeeze of dish soap to each. Swirl gently to mix.
Make a concentrated solution of KI and water.
Demo
Add ~20mL KI solution to 3% cylinder. Watch the bubbles slowly rise and spill out of the cylinder.
Add the same amount of KI to the 30% cylinder and stand back! This reaction goes much more quickly!
Explanation
The potassium iodide catalyzes the decomposition of the hydrogen peroxide into water and molecular oxygen (O2). Also, you may notice an orange/brown color appear when you do this reaction. The color is from the iodine (I2) that is formed when some of the peroxide oxidizes iodide ions. Because oxygen bubbles are formed during the reaction you can actually insert a lit (or freshly blown out) stick into the bubbles and watch it flare up slightly (sorry, no major explosions).
Clean up
Graduated cylinders can be rinsed in a sink using lots of water.
Trash bags can be thrown away.
This reaction produces iodine as a side product, so be sure to wipe up any spills quickly, before it can stain.
Materials
Safety
Preparation
Demo
Explanation
The potassium iodide catalyzes the decomposition of the hydrogen peroxide into water and molecular oxygen (O2). Also, you may notice an orange/brown color appear when you do this reaction. The color is from the iodine (I2) that is formed when some of the peroxide oxidizes iodide ions. Because oxygen bubbles are formed during the reaction you can actually insert a lit (or freshly blown out) stick into the bubbles and watch it flare up slightly (sorry, no major explosions).Clean up